Method of liberating fibers



Jan' 7, 1936' J. A. MANAHAN 2,026,584

METHOD OF LIBERTING FIBERS Filed Jan. 11, 1935 Patented Jan. 7, 1936 PATENT VOFFICE 2,026,584 l ME'rnon or incluirme maas Joseph A. Manahan, Boston, Mass.

Application January 11, `1935, Serial No. 1,288

,19 Claims.

This invention pertainsto an improved method or process of liberating vegetable iiber, useful for textile purposes, from lignin and other connective or incrusting tissues or substances. Among the fiber plants furnishing a plentiful supply of such fibers may be mentioned iiax, hemp, jute, sisal, bagasse, esparto, and ramie or' china grass. In i all of these plants the useful fiber is embedded in, incrusted or coated with, or surroundedby connective tissues frequently of agummy or mucilaginous character which must be destroyed and/or removed before the fiber can be made available for textile purposes. Commercial methods of freeing the fiber contained in some of these plants have been developed, but in most cases such methods are very -slow and laborious and the nature of the treatment is often such as to impair the quality of the fiber, producing degenerated cellulose, low yield, loss of ber strength or decrease in length of staple, whilc'as respects some of such flber plants, for example china grass, apparently no commercially successful method has heretofore beenL found.

Ramie or china grass (Boehmeria m'vec) is a native of Eastern Asia, belonging to thenettle family and has a fiber of great length, which when freed of the abundant and very gummy connective tissue is of a beautiful silky lustre, and capable of being spun into fine yarns. This plant is easily cultivated, and the raw material, ready for ber liberation, may be produced. very cheaply.

Lam aware that attempts have been made tov liberate fiber of textile staple from some of the plants above mentioned by the use of chemicalreagents, with the object of hastening and/or improving upon the older processes which depend largely upon slow bacteriological or mechanical operations, and which at best produce but a low yield of useful liber, but so far as I am aware none of such chemical processes has been commercially successful. After a long series of experiments I have now devised a process capablel of application for the liberation of textile fibers from any or all of the above-named plants, as well as others, and which is especially useful in the treatment of the more diiiicult materials such as ramie, whereby useful ber of high quality, long staple and substantially unimpaired strength may easily and rapidly be produced. For example, long staplesubstantially white fiber having a soit feel, silky lustre and capable of being spun and woven on usual cotton or woolen machinery may be produced from raw ramie at a cost not substantially exceeding that of cotton of equivalent staple.

By way of illustrative example, in the accompanying drawing I 4have indicated my improved process as applied to the preparation 'of ramie aber, and in the drawing,

Fig. 1 is a view showing the general appearance of the dry, coarse, stiff, and straw-like raw ramie cut to a predetermined length ,ready for treatment, in accordance with my improved process;

Fig. 2yis a similar view showing the liberated 5 ber ready for delivery to usual textile machinery; and i Fig. 3 is a diagrammatic representation of a preferred order of steps comprised in my improved process.

While as above noted, my improved process is applicable to the liberationY of fibers, and in par-v ticular bast fibers, from plants of many types, some of which have been specifically enumerated, I will describe it with particular reference to the liberation of fiber from ramie or china grass, with the understanding that a .generally'similar process isvapplicable to the liberation of fibers from other plant materials, which in most instances are more readily liberated from their con- 20 nective tissues than is ramie. l

With this understanding my present process preferably involves the following steps, it being noted that the dry raw material as received is of considerable length, averaging for example, more 25 than twelve inches,'and that since uniformity of ber length is conducive to the production of yarn of high grade, and since existing cotton or woolen machinery is designed for Working ber which is comparatively short, I nd it desirable, 30 though not essential, as a preliminary step in my process, to cut up the raw'stock toa substantially uniform length, selected in accordance with the nature of subsequent treatment to which the liberated fiber is to be subjected.

However, this preliminary step of cutting up the raw stockmay be omitted and the raw material, as received, regardless of length, may be subjected directly to the chemical treatment about to be described.

Referring to the drawing, Fig. l shows the raw material l as having been cut to uniform length, for example one and one-half inches, if the material is to be worked upon cotton machinery. lIhis raw material is dark in color, stiff, straw-like, and harsh, and in coarse strands of cohering fibers or bundles of non-uniform cross section and diameter.

Whether or-not the raw material is cut to uniform lengths I now proceed to treat the material 50 with a hot dilute water solution of a neutral soap.

a tallow soap,lpreferably,a one per cent. solution being preferred, and this liquor is maintained substantially at 212 F. during the treat` ment of the raw material, which lasts for a period n of. approximately thirty minutes. While a soap solution, diluted to-one per cent. soap, is effective,

I have found that thel percentage of soap may be seems to have little beneficial effect,v but I believe that a solution substantially less than one per cent.` soap, is not desirable. The process may be Carried Out in 8. mtary drum, 01' other applOpl'late receptacle, for example, capable of being turned iirstv in one direction and then .in the other, or of being rotated continuously in one dirction, as desired. For most eiIective results I believe that the receptacle should be arranged to turn about a. vertical axis. as proper circulation of the liquid may thus be obtained withoutnnduly tangling the iiber, but it is to be understood that any suitable apparatus in which the material may be exposed to the actionsof the hot reagent liquor may be employed. If the receptacle turn continuously in one direction, it may be furnished with relatively ixed blades or other stirring devices to assure rapid circulation of the liquid. Preferably the drum is driven at a rateof approximately three to four turns per minute during the period while itis undergoing treatment.

As a further safeguard against snarling or tangling theilbers,lmayplacetheminporous bags, nets, or perforate baskets or other receptacles and circulate the liquid in one or opposite directions through such porous or perforate containers, for example by a pressure pump, as in certain well known systems of dyeing.

At the end of this period the soap solution is drained off and the container is immediately lled withiot water containing approximately one per cent of a mild alkaline salt capable of 'softening the gummy and incrusting substances surrounding the ber. Preferably I use trisodium phosphate (NasPO4.12HzO). The drum is again driven at approximately the same rate for about Y forty minutes, after which the liquid is drained oi without opening or uncovering the drum. The drum is immediately filled a second time with a similar hot solution of trisodium phosphate, and the operation repeated for another period of approximately forty minutes, the temperature of thedrum contents being kept at approximately 212 F. throughout the treatment with the alkaline reagent. It is to be noted that during treatment with the alkaline trisodium phosphate, after a previous soap treatment, a violent foaming rmyrsubstance.

takes place, and this foaming is, I believe, an important factor in separating the gummy and other extraneous substances from the usefulfilber, the foam perhaps acting more or less mechanically to support the gummy materials out of contact with the bers, or to emulsify such gummy materials and prevent recoalescence of the gum- The liquid is again drained oif without uncovering the drum, and the brous material is repeatedly rinsed in plain water at boiling temperature and drained, as many as seven rinsing wa.- ters preferably being employed; the drum being turned in one direction at a rate of approximately seven revolutions per minute for a period of iive minutes during each rinsing.

After draining off the inal rinsing water, the

- drum is lled with a hot one per cent. soap solution similar to that ilrst employed-but with the addition of some suitable softening reagent, usually of a waxy or oily nature, for example one-tenth of one per cent. of coconut oil, and with the further addition of approximately one-tenth of one per cent. of calcium chloride (CaClzl The drum is again driven for approximately fifteenV minutes while keeping the temperature of the contents at` approximately 212 F. and. then drained, and the flbennow completely freed from` what hysrosoopic by reason of the calcium.

chloride treatment, and having the necessary softness for machine operation by reason of the smallpercentageofoilorwaxappliedpriorto drying. Moreover, since the fibers are all of substantially the same predetermined length, it is A,

possibletoworkthemintoyarnwithfarless difiiculty or waste, than is Vpossible with nbrous materials of non-uniform character.

In treating nbrous materials. other than ramie, I find that it may be desirable to vary the length of the several periods of treatment from those above instanced. For example, in treating sisal the treatment in the trisodium phosphate bath may be of the order o1' one hour's duration, while in treating 'iiax and hemp each period in the trisodium phosphate may be of the order of forty minutes. The other treatments may likewise be varied in length in substantially the same proportion. l

I am aware that it has previously been proposed to employ trisodium phosphate as a ber liberating medium for paper making, where a very short staple, unsuitable for textile purposes, is required, but for some reason unknown to me a single treatment with this reagent alone apparently fails when applied to the liberation of bast nber for textilepurposes,atleastona commercial scale. While I do not know the exact reason for this failure, I have observed that `the trisodium phosphate solution appears to have a marked solvent effect upon the connective tissue during a certain period oi.' treatment, after which, perhaps, saturation takes place, and that thereafter the action appears to be reversed and the gummy material is redeposited upon the fiber, causing the ilber to adhere in masses and leaving it in a condition wholly unsuitable for textile purposes. On the other hand, if the raw material be first treated with a soap solution, as above described, and particularly if the trisodiuml phosphate treatment be divided into a plurality of successive stages, each terminating before the saturation period is reached, and if precautions be observed to prevent the temperature oi the material from dropping substantially in the intervals between successive steps in the operation, the fiber is completely freed from the gummy material even though the period of treatment may vary very Y considerably, and there is apparently no danger of a re-precipitation of the gummy substance upon Vthe fiber after it has once been removed. Possibly, the observed effect may be due to a physio-chemical action,-i. e., a chemical or solvent action and a physical or emulsifying action, in which some of the reagent material may be partly ionized so as to become eii'ective in dissolving the gummy substance, while on the other hand, the soap, being a colloid, may act to disperse the gum and subsequently act as a stabilizer to prevent recoagulation of the latter. I prefer, as above described, to carry out thetreatment with the trisodium phosphate in two or more successive stages, using a fresh solution at each stage.

' wml r believe um the second trtmeia with lthe soap solutionpand the calcium chloride and oil may, under some circumstances, be dispensed with, I nd that by treating the liberated nber land more pliable and the addition of the calcium chloride, even in very small amount, to the solution. makes the nber somewhat hygroscopic so that it absorbs sufficient moisture from the air to keep it from `becoming harsh and brittle, and serves as a mordant to assist in drying.

I have found that this or an' equivalent step `is very 'desirable to the proper working of the fiber during the subsequent process of yarn andcloth manufacture.

I have hereinabove referred to the use of trli,

sodium phosphate as the preferred liberating reagent, and have found that its mild alkaline action is conducive to the best results thus far obtained. However, desirable though less valuable results (from thecommercial standpoint at least) may be obtained by the use of other soluble l alkaline reagents, for exampletripotassium phosphate (KaPOi), sodium carbonate (NasCOalf borax (NazBlO'z) or ammonium sulphide. ((NHosS), the substances which I have thus found useful for the purpose falling within the general category of mild alkaline salts.

While I have found a soap solution to be very effective for the purpose of pretreating the fiber before cooking it with the alkaline reagent, I have observed that certain other substances, for example naphthalic acid, castor or coconut oil, having an emulsifying action, in the presence of alkali, upon the gummy substances of the plant,

. may be employed in place of the soap, and-I regard emulsifying reagents in general as useful in this particular.

Furthermore, while I havementioned calcium chloride as a desirable hygroscopic agent, I may instead use sodium chloride (NaCl), ethyleneglycol or glycerine with good results, vand believe that any cheap hygroscopic substance, harmless to fiber color or strength might be employed. I also contemplate the use of oils or waxes, which may be sprayed on or otherwise applied to the fiber, for example, after drying, as substitutes for the soap or the hygroscopic substance, or both in the final stage of the process, such oils or waxes,

`for example, sulphonated castor or coconut oil,

` being well known in the' textile arts as reagents -dyes with the greatest ease.

for softening bers and making them more amenable to the spinning process.

I further contemplate an increase in the number of successive treatments with the alkaline reagent, either with or without a decrease or increase in the `length of each period of treatment -as within .the scope of the invention.`

.After the rinsing operation the ber is very light in color, quite curly or crinkly, resembling the best cotton or wool in this particular, and, being even more absorbent than cotton, is veryreadily bleached-to a dazzling white, and takes 4 3 l. That method of liberating' plant fiber fromconnective tissue which comprises treating the raw material with water containing an emulsifving agent, thereafter treating the material with a water solution of a mild alkaline salt, rinsing the material, and treating the material with a softening agentprior to spinning.

2. That method of liberating plant ber froml connective tissuewhich comprises violently agi` tating the raw material in hot -water containing a .colloidal emulsifying agent until the fiber is thoroughly's'aturated with said agent. drawing oil excess fluid, agitating v,the drained material in a hot aqueous solution of an alkaline salt of phos phoric acid, draining and rinsing the material, treating the material with a hygroscopic agent, and drying the material. -v

3. 'I 'hat method of liberating .plant fiber from connective tissue whichl comprises as steps sub- Jecting the raw material tohot water containing a reagent capable oi' emulsifying the gummy substances contained inthe connective tissue after liberation, drawing off' the vsurplus liquid, agitating the material'in a hot solution of a mild alkaline salt capable of softening and separating the gummy substances from the fiber, draining E the liquid, rinsing the material in hot water, and drying the material.

,4. That method of Vliberating plant fiber from connective tissue which comprises keeping the material' at a temperature approximating v212" stances-of the connective tissue when such gum-l my substances are liberated, until the material is saturated with said agent, vthereafter agitat- .ating the raw material withy water containing soap in solution, thereafter treating the material with water containing trisodium phosphate in solution, and-rinsing and drying the material.

6. That method of liberating plant fiber from connective` tissue vwhich comprises as steps saturating the raw material with hot water containin g substantially one per cent. of soap in solution, thereafter treating the material with hot water containing approximately one, per cent. of

trisodium phosphatein solution, rinsing the mavteria, again treating it with a hot soap solution,

and drying the material.

7. That'method of liberating plant fiber from connective tissue for textile purposes which com- Aprises as steps treating the raw material with a hot aqueous solution of soap, thereafter-.treating the material with a hot aqueous solution of trisodium phosphate, rinsing the material, treating the material with a hot aqueous soap solution containing a hygroscopic substance, and drying the material.

8. That method of liberating plant fiber for textile purposes which comprises as steps treating the rawmaterial with hot water containing substantially one per cent. of soap in solution, thereafter treating the materialA with hot water containing approximately one per cent. trisodium phosphate in solution, rinsing the material with h ot water,again treating the material with hot water containing approximately one per cent. ofl

Cil

soap in solution and also approximately onetenth oi one per cent. of calcium chloride in solution, and thereafter drying the material.

9. That method of liberating plant ber for textile purposes which comprises as steps cutting the previously dried raw material into substan` tially uniform predetermined lengths, agitating the raw material thus cut into uniform lengths in a hot dilute soap solution, draining off the solution, treating the material with a hot dilute solution of trisodium phosphate, rinsing the material in hot water, treating the material with a dilute soap solution containing a hygroscopic substance, and thereafter drying the material.

l0. That method of liberating plant ber for textile purposes which comprises as steps placing the cut raw material in a perforate container, causing a hot dilute lsoap solution to circulate through said container for a period of the order of thirty minutes, drainingoif the solution, successively circulating through' the material, for periods of approximately forty minutes, respectively, hot dilute solutions of trisodium phosphate,

subjecting the material to repeated rinsings in hot water with drainings between the several rinsings, agitating the material in a hot dilute soap solution containing calcium chloride, and drying the material.

1l. That method of liberating plant ber from connective tissue which comprises as steps agitating the raw material in water at approximately 212 F. containing substantially one per cent. soap fora period of the order of thirty minutes, draining oi the solution, agitating the material in a one per cent. water solution of trisodium phosphate at a temperature of approximately 212 F. for a period of approximately forty minutes, draining oi the solution, repeating the boiling and agitation in a solution of trisodium phosphate for a similar period, draining oi the solution, rinsing the material by agitating it for periods of approximately ve minutes each, with intermediate drainings, but without uncovering the receptacle, in plain hot water, agitating the material for approximately fteen minutes in hot water containing one per cent. soap and one-tenth of one per cent. calcium chloride in solution, draining ofi the solution and air-drying the material without substantial agitation.

12. That method of nberaung plant aber from connective tissue which comprises as steps placing the raw material in a perforate container, forcing a uid reagent to circulate through the container, said reagent being a boiling solution of trisodium phosphate, discontinuing the treatment with said reagent before the latter has become saturated with gummy constituents of the raw material, circulating a rinsing liquor through the material, and repeating the above steps until the ber has been substantially freed from gummy substances.

13. That method of liberating plant ber from connective tissue which comprises as steps circulating a boiling solution of trisodium phosphate through the raw material to be treated, discontinuing such circulation of the solution before the latter has become saturated with gummy substances, draining oif the solution, rinsing the material under treatment, and repeating the above steps until the ber has been substantially freed from gummy substances.

14. That method of liberating plant ber from connective tissue which comprises as steps circulating a hot solution of trisodium phosphate through the raw material to be treated for a period less than that beyond which re-precipitation 5 of gummy substances would begin, draining off the solution, rinsing the material in hot water without permitting the temperature of the material substantially to fall, and repeating said steps until the ber has been substantially freed from the gummy substances.

15. That method of liberating plant ber from gummy connective tissue which comprises as steps agitating the raw material in a boiling water-solution of trisodium phosphate for a period of approximating, but less than, that beyond which reprecipitation of gummy substances would begin, draining oil the solution and rinsing the material in hot water without permitting the material substantially to drop in temperature, repeating said steps until the ber is substantially free from gummy substances, and'thereafter treating the ber with a hygroscopic agent.

16. That method of liberating plant ber from connective tissue for textileV purposes, which comprises as steps subjecting the raw material to the action of water at approximately 212 F. and containing approximately one-tenth of one per cent. of trisodium phosphate in solution, rinsing the material with hot water without permitting the temperature of the material substantially to drop and without exposing it to the air, repeating the preceding steps, thereafter further rinsing the material in hot water, and drying the material.

17. That method of liberating plant ber from connective tissue for textile purposes, which comprises as steps causing water at approximately 212 F. and containing approximately one-tenth of one percent. of trisodium phosphate in solution to circulate in contact with the raw material for 40,. a period of appproximately forty minutes, draining off the liquor without permitting the temperature of the material substantially to drop, circulating a fresh trisodium phosphate solution of substantially the same strength and temperature 45 through the material for a similar period, again draining o the liquor without permitting the temperature to drop, and repeatedly rinsing the material with hot water.

18. That method of liberating plant ber from 5o,

connective tissue which comprises as steps repeatedly subjecting the material to be treated to a boiling water-solution of a mild alkaline salt, each successive treatment being in a. fresh'solution and each such treatment being followed by a rinsing in hot water, the entire process being carried out without substantial drop in temperav ture of the material from beginning to end and without free exposure of the material to the open' air.

19. That method of liberating plant ber from connective tissue which comprises as steps rst treating the raw material with a foam-producing reagent, thereafter treating it with a boiling solution of a mild alkaline salt, rinsing the material4 without permitting its temperature substantially to drop, again treating it with a boiling solution of a mild alkaline salt, rinsing the material, treating it with a softening reagent, and drying the material.

JOSEPH A. MANAHAN. 

